The present invention relates to removable filters for use in water heating vessels such as electric water kettles, coffee makers, and the like.
Removable filters for use in water kettles for removing scale and the like are known, examples of such for use in electric water kettles being described in GB-B-2251547. A filter disclosed therein consists of a plastics frame having windows covered by fine filter mesh which is positioned within the water-containing body of the kettle overlying the output spout so that water heated in the kettle passes through the mesh of the filter when being poured out through the spout. The interior of the kettle body and the frame of the filter are provided with cooperating engagement means for removably mounting the filter in the kettle in sealing manner. This enables the filter to be slid into, and retained in, the kettle body in the desired position and also enables the easy removal of the filter by reverse action for cleaning or replacement purposes. In use, the mesh of the filter prevents the passage through the spout of particulate and sedimentary materials, and especially scale (generally calcium carbonate) produced when boiling water which can lead to a scum being formed on the surface of the water, particularly when the kettle body is formed of a plastics material since the extent of metal surfaces, to which such has a tendency to adhere, is then less. Thus, undesired sedimentary material is trapped within the kettle. The filter can be periodically removed and washed to remove accumulated scum and sediment material and the interior of the kettle similarly rinsed to remove loose material. Over a period of time, which is dependent on the hardness of the water used, scale may form on the filter mesh causing clogging but then the filter can readily be removed and replaced by a fresh unit.
Such a filter has proved to be effective in preventing scum and particulate material being poured out with the water. However, scale will continue to be formed on interior surfaces of the kettle body which in the case of kettles with bodies of plastics material will usually be the surfaces of metal components, such as an immersion heater element or an exposed metal bottom wall surface to which a concealed type electric heating element is fixed, since scale appears to form much more readily on metal surfaces rather than the plastics materials commonly used for the kettle bodies. Accumulated scale formation on the heating element or bottom metal plate not only looks unsightly but can also impair the operational effectiveness of the heating element.
It has been known also for some time to use in water kettles a scale collector comprising a body of stainless-steel wire or mesh compacted into the form of a small ball-like block which is simply dropped into the kettle and which serves as a scale attractor or precipitator upon which scale is encouraged to form rather than other metal components such as the element. However, movement of this block within the kettle body can cause damage through scratching and abrasion to the element and wall surfaces of the kettle body, and the mesh of a filter if fitted. If a filter is not fitted, the block may even obstruct the spout and prevent the free flow of water therethrough.